When communication is performed in a WLAN system, errors of transmitted information bits often occur serially. However, channel coding works only in a case of detecting and correcting a single error or a short string of errors.
To resolve the foregoing problem, an interleaving processing technology is used to process transmitted data bits. After the interleaving processing technology is used, consecutive transmitted data bits are scattered, and the transmitted data bits can be sent in a non-consecutive manner. In this way, even if a string of errors occurs in a transmission process, when a message of a successive bit string is restored, the errors become a single (or relatively short) error. In this case, the error is corrected by using a correction function of the channel coding, so that the original transmitted data bits can be restored more accurately.
In the 802.11a/g protocol, sub-interleaving processing needs to be performed on the transmitted data bits twice. In the 802.11n/ac/ah protocol, sub-interleaving processing needs to be performed three times. An interleaving processing parameter of any time of sub-interleaving processing may be determined according to a quantity of data subcarriers, that is, when the quantity of data subcarriers changes, the interleaving processing parameter also needs to change accordingly.
In addition, in the 802.11a/g/n/ac/ah protocol, an OFDM (Orthogonal Frequency Division Multiplexing) technology is used to perform data transmission. OFDM is a multi-carrier technology in which a frequency domain is divided into multiple mutually orthogonal data subcarriers, modulated signals that are corresponding to transmitted data bits and that are obtained after interleaving processing and modulation are respectively mapped to corresponding data subcarriers for transmission, and a quantity of data subcarriers is fixed.
To further improve transmission efficiency of a multi-user system, an orthogonal frequency division multiple access (OFDMA) technology is introduced into a next-generation WLAN standard. According to OFDMA, a transmission bandwidth is divided into a series of orthogonal subcarrier sets that do not overlap with each other, and different subcarrier sets are allocated to different orthogonal frequency division multiple access users, to achieve multiple access. Compared with the OFDM technology, an OFDMA system may dynamically allocate an available bandwidth resource to a user in need, thereby facilitating optimized utilization of system resources. Different subcarrier sets in each OFDM symbol are allocated to different users. Consequently, an original fullband interleaving solution causes data interleaving between different users, thereby affecting optimized user subcarrier allocation. Therefore, in the next-generation WLAN technology, an effective bit interleaving solution needs to be redesigned for a frequency band occupied by each user in the OFDMA system, to improve system performance with a lowest possibility of increasing system complexity.